Methods of and apparatus for aligning electrodes in a process chamber to protect an exclusion area within an edge environ of a wafer

ABSTRACT

Positional relationships are established in a process chamber. A base is configured with a lower electrode surface to support a wafer, and an upper electrode has a lower surface. A drive mounted on the base has a linkage connected to the upper electrode. A fixture placed on the lower surface moves into a desired orientation of the lower electrode. With the upper electrode loosely connected by the linkage to the drive, the fixture transfers the desired orientation to the upper electrode. The linkage is tightened to maintain the desired orientation, the fixture is removed and a process exclusion insert is mounted to the upper electrode. The drive moves the upper electrode and the insert to define an inactive process zone between the upper electrode and the wafer on the lower electrode to protect a central area of the wafer during etching of a wafer edge environ around the central area.

RELATED APPLICATION

This application is related to U.S. Pat. No. 7,575,638 entitled“Apparatus For Defining Regions of Process Exclusion and ProcessPerformance In A Process Chamber”, filed on Feb. 2, 2007, referred to asthe “Related Application”. The disclosure of the Related Application isincorporated by reference.

BACKGROUND

1. Field

The present invention relates generally to semiconductor manufacturingand, more particularly, to apparatus for aligning electrodes in aprocess chamber to define regions of process exclusion and of processperformance in the process chamber for manufacturing semiconductorwafers.

2. Description of the Related Art

Vacuum processing chambers have been used for etching materials fromsubstrates and for deposition of materials onto substrates. Thesubstrates have been semiconductor wafers, for example. In general,accurate processing (and thus high yields of devices) is expected tooccur in a central area of the wafer. Numerous difficulties areexperienced in attempting to accurately process the wafer on a portionof a top, or upper, surface of the wafer, wherein that portion isbetween the central area and a peripheral edge of the wafer thatsurrounds the central area. Such difficulties are significant enoughthat an “edge exclusion area” has been defined between the central areaand that peripheral edge of the wafer surrounding that central area. Noattempt is made to provide acceptable devices in that edge exclusionarea.

Additionally, during the desired processing of the central area,undesired deposits, materials, or process-by-products (collectively“undesired materials”), accumulate or result on the edge exclusion areaof the upper surface of the wafer, and on a peripheral edge area of theperipheral edge of the wafer, and below the peripheral edge area onto abottom area of an opposite (bottom) surface of the wafer. Those threeareas are not to be processed to form devices. The edge exclusion area,the edge area, and the bottom area are referred to collectively as the“edge environ”. These undesired materials may generally accumulate onthe edge environ. The accumulation may be so extensive that the desiredprocessing of the central area must be interrupted because, in general,it is desired to keep the edge environ substantially clean, so as toavoid flaking of material particulates that may redeposit back onto theactive device regions on the upper surface of the wafer. Such flakingcan occur during any number of wafer handling or transport operations,and thus, it is a general desire that the edge environ be periodicallycleaned (e.g., etched) or monitored for cleaning (i.e., etching) duringthe numerous processing operations used to fabricate integrated circuitdevice chips, from the processed wafers. The desired processing of thecentral area has been interrupted to perform such periodic cleaning inan attempt to remove the undesired materials from the edge environ, e.g.from the entire edge environ, and e.g., to perform such removal withoutdamaging the devices.

In view of the foregoing, there is a need to assure that such neededapparatus is accurately aligned before use, so that in use the apparatusresults in accurate (e.g., uniform) removal of the undesired materialsfrom the entire edge environ, without removing materials from orotherwise damaging the central area.

SUMMARY

Broadly speaking, embodiments of the present invention fill these needsin the context of embodiments of the Related Application that providesemiconductor manufacturing apparatus configured for defining separateregions of process exclusion and process performance in a processchamber for manufacturing the semiconductor wafers. The apparatus of theRelated Application may be configured so that a process such as etchingis excluded from the central area of the wafers, and a process such asetching is allowed to be performed on the wafer only on the edgeenviron. Embodiments of the present invention fill these needs byassuring that electrodes of such needed apparatus are accurately alignedbefore use, so that use of such needed apparatus results in accurate(e.g., uniform) removal of the undesired materials from the entire edgeenviron, without removing materials from or otherwise damaging thecentral area.

Embodiments of the present invention may provide apparatus for aligningfirst and second spaced reference surfaces in a wafer process chamber. Afixture may be configured with an upper fixture reference surface and alower fixture reference surface parallel to the upper fixture referencesurface. The lower fixture reference surface may be configured to besupported on the first spaced reference surface to orient the lowerfixture reference surface and the upper fixture reference surfaceparallel to the first spaced reference surface. The upper fixturereference surface may be configured to support the second spacedreference surface to orient the second spaced reference surface parallelto the upper fixture reference surface and parallel to the first spacedreference surface.

Embodiments of the present invention may also provide apparatus fororienting an upper electrode relative to a desired existing orientationof a lower electrode in a wafer process chamber, each electrode beingconfigured with a reference surface. A fixture may be configured with anupper nest and a lower nest, the upper nest being configured with anupper fixture reference surface and an upper wall. The lower nest may beconfigured with a lower fixture reference surface and a lower wall. Thelower fixture reference surface may be parallel to the upper fixturereference surface. The upper wall may be coaxial with and parallel tothe lower wall. Each of the upper nest and lower nest may be configuredto receive at least a portion of the respective upper and lowerelectrode reference surface. The nests orient the upper electroderelative to the desired existing orientation of the lower electrode byaligning the lower fixture reference surface and the upper fixturereference surface parallel to the lower electrode reference surface andby centering the upper electrode relative to the lower electrode.

Embodiments of the present invention may provide apparatus forestablishing positional relationships in a process chamber forprotecting an exclusion area within an edge environ of a wafer.Apparatus may include a lower electrode configured with a firstelectrode reference surface to support a wafer to be processed on theedge environ. A base may be configured with a frame, the base beingconfigured to mount the lower electrode with the first electrodereference surface in a desired orientation for processing the edgeenviron and not the exclusion area of the wafer. A process exclusioninsert may be configured with parallel first and second insert surfacesfor protecting the exclusion area from processing. An upper electrodemay be configured with a second electrode reference surface to removablymount the insert with the first insert surface against the secondelectrode reference surface and the second insert surface parallel tothe second electrode reference surface. An alignment fixture may beconfigured for use with the upper electrode and the lower electrodeinstead of the insert. The fixture may be configured with an upperfixture reference surface and a lower fixture reference surface parallelto the upper fixture reference surface. The fixture may be configured sothat the lower fixture reference surface mates with the first electrodereference surface to support the fixture on the lower electrode with thelower fixture reference surface and the upper fixture reference surfacein the desired orientation. The fixture may be configured so that theupper fixture reference surface mates with the second electrodereference surface to removably support the upper electrode on thefixture with the upper electrode reference surface in the desiredorientation parallel to the upper first electrode reference surface. Anadapter may be between the frame and the upper electrode, the adapterbeing adjustable between a loose configuration and a tightconfiguration. In the loose configuration the adapter defines variablealignment spaces between the adapter and the frame to allow the upperelectrode to be supported on the fixture in the desired orientation. Inthe tight configuration the adapter secures the upper electrode to theframe with the upper electrode in the desired orientation to permitremoval of the fixture and mounting of the insert on the upper electrodewhile the upper electrode remains in the desired orientation to protectthe exclusion area from processing.

Embodiments of the present invention may provide a method of orientingan upper electrode relative to a lower electrode having a desiredexisting orientation in a process chamber to define active and inactiveprocess zones in the process chamber for processing a wafer. The methodmay comprise an operation including configuring each electrode with areference surface. A lower electrode reference surface may be in thedesired existing orientation. An upper electrode reference surface is tobe oriented parallel to the lower electrode reference surface. Anotheroperation may temporarily hold the upper electrode reference surfaceoriented parallel to the lower electrode reference surface. Yet anotheroperation secures the upper electrode to a drive to mount the upperelectrode reference surface parallel to the lower electrode referencesurface.

It will be obvious; however, to one skilled in the art, that embodimentsof the present invention may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail in order not to obscure the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will be readily understood byreference to the following detailed description in conjunction with theaccompanying drawings in which like reference numerals designate likestructural elements, and wherein:

FIG. 1 is a schematic elevational view of a process chamber of anembodiment of the present invention in which a plurality of positionalrelationships may be established between a base, such as a bottom, orlower, electrode or chuck, and an upper, or top, electrode.

FIG. 2A is a view of an enlarged portion of FIG. 1 in which one of thepositional relationships is illustrated between a first referencesurface of the lower electrode and a second reference surface of the topelectrode.

FIG. 2B is a cross sectional view taken along line 2B-2B in FIG. 2A,illustrating a toroidal configuration of an etching region definedbetween the lower electrode and the top electrode.

FIG. 2C is a cross sectional view taken along line 2C-2C in FIG. 2B,illustrating an enlarged view of the top electrode configured with aprocess exclusion insert having the second reference surface at a centerarea, the second reference surface being in the second positionalrelationship with the first reference surface, showing a generallyC-shaped cross sectional configuration of one embodiment of the toroidaletching region.

FIG. 3 is a cross sectional view illustrating a wafer supported by thelower electrode, showing top and bottom edge defining rings to enableetching of an edge environ of the wafers.

FIG. 4 is a plan view taken on line 4-4 in FIG. 1, showing the spacingaround a wafer axis of sections of a drive that operates throughsections of an adjustable linkage for moving the reference surfaces intothe positional relationships.

FIG. 5A is an enlarged cross sectional view taken on line 5A-5A in FIG.4 showing one section of the linkage in a loosened configuration tofacilitate orienting the second reference surface with respect to thefirst reference surface that is in a desired existing orientation.

FIG. 5B is an enlarged cross sectional view showing part of the linkageshown in FIG. 5A, illustrating the linkage in a tightened configurationto hold the second reference surface oriented with respect to the firstreference surface.

FIG. 6 cross sectional view taken on line 6-6 in FIG. 4, showing theconfiguration of one of the sections of the drive.

FIG. 7A is a cross sectional view similar to FIG. 2A, in which theprocess exclusion insert and the rings have been removed, illustrating afixture for use with the electrodes shown in FIGS. 1-3 to orient thefirst and second reference surfaces and establish a desired positionalrelationship between the lower electrode and the upper electrode.

FIG. 7B is a cross sectional view similar to FIG. 7A, illustrating theupper electrode resting on the fixture to orient the second electrodereference surface with respect to the first reference surface.

FIG. 8 is a flow chart depicting operations of a method of oneembodiment of the present invention for orienting the upper electroderelative to a desired orientation of the lower electrode in a waferprocess chamber to define active and inactive process zones in theprocess chamber.

Other aspects and advantages of embodiments of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of embodiments of the presentinvention. It will be apparent, however, to one skilled in the art thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail in order not to obscure the presentinvention.

Embodiments of the present invention described below fill theabove-described needs in semiconductor manufacturing apparatusconfigured for defining separate regions of process exclusion andprocess performance in a process chamber for manufacturing thesemiconductor wafers. For the process exclusion, such apparatus may beconfigured so that a process (e.g., etching) is excluded from thecentral area of the wafers. For the process performance, the exemplaryetching process may be allowed to be performed on the wafer only on theedge environ. Embodiments of the present invention fill these needs byassuring that electrodes of such apparatus are accurately aligned beforeuse. In this manner, such apparatus may be set up so as to excludeetching from the central area of the wafers, the set up allowing theexemplary etching process to be performed only on the edge environ ofthe wafer. Embodiments of the present invention fill these needs so thatas set up with the accurate alignment of the surfaces that define anetching chamber of such apparatus, in use the etching chamber accurately(e.g., uniformly) removes the undesired materials from the entire edgeenviron, without removing materials from or otherwise damaging thecentral area.

FIG. 1 shows a process chamber 50 in which a plurality of positionalrelationships may be established. Generally, the positionalrelationships may be established between a base 52 and a top, or upper,electrode 53 in the chamber 50. In more detail, the base 52 may beconfigured with a lower, or bottom, electrode (or chuck) 54 having afirst electrode reference surface 56 to support a wafer 58 to beprocessed, as by etching or another desired process suitable forremoving the undesired materials from the wafer. The upper electrode 53may be configured with a second electrode reference surface 60 and witha third reference surface 61. The upper electrode 53 is configured toprovide power for processing the supported wafer.

FIG. 2A shows an enlarged portion of FIG. 1, illustrating a first of thepositional relationships between, or with respect to, the firstreference surface 56 and the second reference surface 60. Forestablishing the relationships, FIG. 1 shows a drive 62 mounted on thebase 52 and configured with an embodiment of a linear motor, such as awedge assembly 64, mounted on the base 52. FIG. 1 also shows a linkage66 connected between the drive 62 and the upper electrode 53. Thelinkage 66 may be adjustable to allow establishment of a desiredorientation between the respective first and second reference surfaces56 and 60, e.g., parallelism of the respective first and secondreference surfaces 56 and 60. Tightening of the linkage 66 may alsomaintain that desired orientation while the drive 62 moves the upperelectrode 53 to establish a positional relationship for processing thewafer. The enlarged view of FIGS. 2A & 2C show that moving the upperelectrode 53 may cause the respective first and second referencesurfaces 56 and 60 to move relative to each other. The movement may befrom the first positional relationship (FIG. 2A) to a second positionalrelationship shown in FIG. 2C, and back again.

FIG. 2A shows the upper electrode 53 having a center area 68. The centerarea 68 extends radially as shown by a portion of bracket 68E. The crosssectional view of FIG. 2B shows the center area 68 as being circular andthe wafer 58 having a center at axis X. The center area 68 is notpowered and may be configured from a process exclusion insert 69. FIG. 3shows that the insert 69 may be configured with an inner (or upper)reference surface 691 that is mounted on (i.e. fixed to) the thirdreference surface 61 of the upper electrode 53. The upper referencesurface 691 of the insert is configured with a recess 69R that iscoaxial with the axis X and may be configured as a hole extendingthrough the insert 69. The insert 69 is centered on the upper electrode53 by a projection 53P that is coaxial with the axis X. The projection53P extends into the recess 69R of the insert 69. The recess 69R and theprojection 53P have respective mating cylindrical walls 53W and 69W thatare coaxial with the axis X.

By way of an outer (or lower) surface of the insert 69 opposite to theinner reference surface 69I, the upper electrode 53 is configured withthe second reference surface 60, such that the second reference surface60 may be referred to as an outer reference surface of the insert 69.The respective inner and second reference surfaces 69I and 60 areparallel. Thus, with the inner reference surface 69I of the insert 69mounted on (and secured to) the third reference surface 61, and with theinner and outer reference surfaces 69I and 60 parallel, orientation ofthe third reference surface 61 parallel to the first reference surface56 provides the second (outer) reference surface 60 parallel to thelower reference surface 56. The insert 69 may be fabricated from adielectric such as ceramic, for example. A portion of the center area 68identified by 68X extends radially further outwardly than the insert 69,and is described below.

FIG. 2A shows the insert 69 configured with the second reference surface60 opposite to a central area 70 of the wafer. In the first positionalrelationship shown in FIG. 2A, a space 72 separates the second referencesurface 60 from the first reference surface 56 when the wafer 58 issupported by the lower electrode 54 and centered on the axis X. Thespace 72 is configured extending radially across (or between) the insert69 and the wafer 58, and extends in a vertical, or axial, direction(arrow 74) of the axis X, and this axial extension is sufficient (large)in two respects. One, the space 72 is configured to permit access to thewafer 58 on the lower electrode 54 for loading the wafer on the lowerelectrode and removing the wafer from the lower electrode. Two, thespace 72 is also configured to provide a normal-size process, oretching, zone 76 between the upper electrode 53 and the central area 70of the wafer 58 that is on the lower electrode 54. With this space 72,if the upper electrode 53 were powered, a plasma could light up in thenormal-size zone 76. It may be appreciated that with the normal-sizeprocess zone 76 between the upper electrode 53 and the wafer (resultingfrom the first positional relationship), such plasma would have accessto the central area 70. It may be understood then that the space 72 (andthe normal-size zone 76) may be part of a process chamber cavity 77.

In FIG. 2A, bracket 70E defines a left and a central extent of thecentral area 70 that extends to the axis X. In FIG. 2B, bracket 70Eshows the full extent of the central area 70. FIG. 2A shows that whenthe desired process is for removing undesired materials 78 only fromedge environ 80 of the wafer, and not for removing undesired materials78 or any other materials from the central area 70 where devices may beon the wafer, the plasma in normal-size process zone 76 would beunacceptable because the devices must not be damaged (e.g., by theplasma).

Embodiments of the present invention promote avoiding such damage to thedevices, and promote limiting the plasma to action on edge environ 80that is to be subjected to the processing. FIG. 2C shows the secondpositional relationship, and illustrates the second reference surface 60in close proximity to the central area 70 of the wafer 58 when the waferis supported by the lower electrode 54. Bracket 70E indicates a portionof the radial extent of the central area 70 that extends from the axis Xof the wafer 58. The second reference surface 60 in close proximity tothe first reference surface 56 is almost touching an upper surface 82 ofthe wafer. E.g., surface 60 may be separated from the surface 82 by aspace 84 defined below. FIG. 2C shows that in the second positionalrelationship, the described space 72 (FIG. 2A) no longer exists. As aresult, when portions of the upper electrode 53 are powered, no plasmaaccess to the central area 70 of the wafer 58 is permitted, and there isno normal-size process (etching) zone 76 between the center area 68 ofthe upper electrode 53 and the central area 70 of the wafer 58 on thelower electrode 54. Thus, a plasma may not light up between the centerarea 68 and the central area 70. Instead of the space 72 and instead ofthe normal-size zone 76 of the chamber cavity 77, FIG. 2C shows thatwith the surfaces 56 and 60 in close proximity the space 84 isaxially-thin and defines the chamber cavity 77 as being configured withan inactive etching zone 86 between the central area 70 of the wafer andthe center area 68 of the top electrode 53. The zone 86 defined by thethin space 84 is referred to as an “inactive” etching zone because thecentral area 70 and the center area 68 are so close that a plasma cannotlight up in the thin space 84. Thus, when there are process operationsallowed to be conducted in other portions of the chamber 77, no etchingoccurs in the space 84 and such devices as may be on the central area 70of the wafer 58 are not damaged. This spacing of the central area 70 andthe center area 68 results from the close proximity of the secondreference surface 60 with the first reference surface 56 and mayconfigure the inactive etching zone 86 with a dimension in a directionof movement of the electrode 53 (i.e., the direction of the X axis) ofabout 0.010 inches to about 0.020 inches, for example, and with adimensional tolerance of about plus or minus 0.002 inches.

Embodiments of the present invention promote avoiding such damage to thedevices by aligning the upper electrode 53 with the lower electrode 54to define the desired orientation between the first and second referencesurfaces 56 and 60, e.g., parallelism of the respective first and secondreference surfaces 56 and 60. This alignment of the upper electrode 53with the lower electrode 54 (for that desired orientation) isestablished by the embodiments of the present invention with the linkage66 loosened. With this alignment maintained temporarily, the linkage 66may be tightened and embodiments of the present invention may beremoved. With the insert 69 mounted on the upper electrode 53, thetightened linkage 66 maintains the desired orientation, e.g.,parallelism of the respective first and second reference surfaces 56 and60. In this manner, the desired orientation is maintained when the drive62 then moves the upper electrode 53 relative to the lower electrode 54(e.g., to cause the respective first and second reference surfaces 56and 60 to move relative to each other from the first positionalrelationship, FIG. 2A, to the second positional relationship shown inFIG. 2C, and back again). By maintaining the desired orientation, theaxially-thin space 84 that defines the inactive etching zone 86 isuniformly maintained. In this regard, “uniformly” (and a “uniformspacing”) are defined as the central area 70 and the center area 68being both close and parallel, and with the same distance existingbetween the first and second reference surfaces 56 and 60 measured atvarious distances from and around the axis X. As a result of the uniformspacing, the plasma does not light up in the thin space 84 and thedevices on the central area 70 are not damaged.

The embodiments of the present invention that align the upper electrode53 with the lower electrode 54 not only define the desired orientationbetween the first and second reference surfaces 56 and 60, but alsopromote uniformity of processing of the edge environ 80 that is to besubjected to the processing, e.g., etching. FIG. 2B shows the edgeenviron 80 including a peripheral edge 90 of the wafer. The edge 90 isradially spaced from the axis X of the wafer, e.g., for a 300 mm wafer58, the radial space from the axis X is thus 150 mm. The upper surface82 (FIG. 2C) of the wafer extends radially inward from the edge 90 andincludes the central area 70. A bottom surface 92 of the wafer is belowthe edge 90 and opposite to the upper surface 82. FIG. 2B shows the edgeenviron 80 extending radially inwardly from the edge 90 along an outerannular portion of the upper surface 82. The outer annular portionextends radially relative to the axis X. The amount of this radialinward portion is described below, and may include the above-describededge exclusion area defined between the central area 70 and the edge 90.To indicate that the edge exclusion area is part of the upper surface82, the edge exclusion area is identified by 82EEA in FIG. 2B, and isthus also a part of the edge environ 80. As described above, the edgeexclusion area 82EEA surrounds the central area 70, and in theprocessing of the central area 70 no attempt is made to provideacceptable devices on that edge exclusion area 82EEA.

For clarity of description, in FIG. 2C a curved line 96 indicates anextent of the edge environ 80 (identified there as 80-C, as describedbelow). Line 96 identifies the edge environ as an annular surfaceportion of the outer extremity of the wafer. The wafer axis X is at thecenter of the annular portion. FIG. 2C shows the annular edge environ 80(i.e., the edge 90, and portions of the surfaces 82 and 92) having anaccumulation of the undesired materials 78. FIG. 2B shows some of thematerials on the portion of the upper surface 82 corresponding to theedge exclusion area 82EEA and on the edge 90. Thus, it is the annularedge environ 80 (the annular portion comprising edge 90, and areas, orportions, of surfaces 82 and 92) that is not to be processed to formdevices, and that is to be etched to remove the materials 78. Also, itis the edge environ 80 from which it is desired to have uniform removalof the undesired materials 78, so that complete removal of the materials78 occurs all around the outer annular portion of the wafer, i.e.,complete removal from the edge environ 80. This removal is uniformremoval all around the wafer axis X.

FIG. 1 shows the process chamber 50 defining the chamber cavity 77 thatencloses a lower section of the upper electrode 53 and encloses thelower electrode 54. FIG. 2C also shows that with the second positionalrelationship established, the chamber cavity 77 of the process chamber50 may be configured with a toroidal, or annular, etching region 100defined between the upper electrode 53 and the lower electrode 54. Theetching region 100 defines a configurable active etching, or activeetch, zone 102 shown inside a dash-dot-dash line 102L. An exemplarycross-section of the region 100 is shown defined by the line 102L inFIG. 2C. The annular etching region 100 shown in FIG. 2C is illustratedas being configured with one embodiment of the active etching zone 102having an exemplary generally C-shaped cross section. This C-shapeextends around, or encompasses, the annular edge environ 80 and extendsfrom one end C1 to an opposite end C2. For reference, in FIG. 2A the endC1 of the line 102L identifying the active etching zone 102 is shown. Inthe cross section of FIG. 2B the end C1 and line 102L are shown as beingcircular and extending around the axis X, indicating the radial locationof the outside of the toroidal region 100.

The active etching zone 102 is also shown adjacent to the edge environ80 (see 80-C). In FIG. 2A the section line 2B-2B also crosses the line102L. Line 102L is also shown in FIG. 2B extending radially outward ofthe edge 90 to indicate the radial amount (or extent) of the annularetching region 100. The exemplary generally C-shaped cross section ofthe region 100 is a region of plasma light up. In FIG. 2C the region 100with this exemplary cross section is shown adjacent to a topradially-extending length L1 of the wafer upper surface 82. For thisexemplary C-shaped cross section, L1 identifies a radially-extendingportion of the upper surface 82 from which it is desired to remove theundesired materials 78. The region 100 is also shown adjacent to theedge 90 of the wafer 58. For this exemplary C-shaped cross section, theedge 90 is also a portion of the wafer surface from which it is desiredto remove the undesired materials 78. The region 100 extends from C1along the length L1 of the upper surface 82 (i.e., of edge exclusionarea 82EEA), around the peripheral edge 90 and to the bottom surface 92of the wafer. The region 100 extends along a bottom length L2 of thebottom surface 92 to C2. For this exemplary C-shaped cross section, L2identifies a radially-extending portion of the lower surface 92 of thewafer 58 from which it is desired to remove the undesired materials 78.In this example, the edge environ 80 of the wafer 58 thus includes thelengths L1 and L2 and the edge 90, and for ease of description isidentified in FIG. 2C as 80-C. The active etch zone 102 thus surroundsthe edge environ 80-C.

In review, these combined configurations of the lower electrode 54 andthe upper electrode 53 define the annular etching region 100 as anannular process chamber region between the lower electrode 54 and thetop electrode 53. The region 100 defines the active etch, or activeetching, zone 102 that is part of the chamber cavity 77. The embodimentsof the present invention that align the upper electrode 53 with thelower electrode 54, and that promote uniformity of processing of theedge environ 80 that is to be subjected to the processing, e.g.,etching, are configured so that the alignment of the upper electrode 53with the lower electrode 54 results in the annular etching region 100and the active etch zone 102 extending uniformly around (and separatefrom) the inactive etch zone 86. In more detail, as viewed in FIG. 2C,the above-defined uniform spacing provides the same distance 86D betweenthe first and second reference surfaces 56 and 60 measured at variousradial distances from the axis X so that the plasma does not light up inthe thin space 84 and the devices on the central area 70 are notdamaged. That uniform spacing providing the same distance 86D alsouniformly defines the active etch zone 102 and promotes uniformity ofprocessing of the edge environ 80-C all around the axis X.

With the distances 84 the same at the exemplary radial distances fromthe axis X for the inactive zone 86, FIG. 2C shows a distance 102D1between a configurable portion, or ring, 110 of the upper electrode 53and a configurable portion, or ring, 120 of the lower electrode 54. Bythe embodiments of the present invention that align the upper electrode53 with the lower electrode 54, the distance 102D1 is the same whenmeasured at various places around the axis X and within the active etchzone 102. Also, a distance 102D2 is the same when measured at variousplaces around the axis X and within the active etch zone 102, and adistance 102D3 is the same when measured at various places around theaxis X and within the active etch zone 102. As a result, the embodimentsof the present invention that align the upper electrode 53 with thelower electrode 54 result in the action of the plasma on the edgeenviron 80-C being uniform all around the axis X.

One exemplary configuration of the active etch zone 102 is shown in FIG.2C in connection with etch defining rings 110 and 120, and theabove-described distances 102D1-102D3 are shown related to these rings110 and 120. FIG. 2C shows a border B between the end C1 of theexemplary annular etching region 100 and the exemplary inactive etchzone 86 described above. Also, FIG. 2B indicates the radial location ofthe border B, and shows the border as being circular and adjacent to theend C1 of the line 102L that identifies the active etch zone 102. Theborder B may be located radially relative to the axis X according to awafer specification, and is generally outward from the outside of theinsert 69 of the top electrode 53. The distances 102D1-102D3 that are tobe the same may be measured at any of various places around the axis X.

The configuration of each of the rings 110 may relate to theabove-described desired orientation provided by the linkage 66 betweenthe first and second reference surfaces 56 and 60. An example of suchdesired orientation was the first and second reference surfaces 56 and60 being parallel. As described with respect to the ring 110, a top etchdefining ring, the configuration of each of the rings 120 may alsorelate to the above-described exemplary desired orientation, e.g., thefirst and second reference surfaces 56 and 60 being parallel. FIG. 2Cshows one embodiment of the ring 120, a bottom etch defining ring, ofthe chuck 54 configured with a bottom annular recess 122. The bottomannular recess 122 is configured with a wall 124 located radially fromthe axis X to provide the length L2. The bottom annular recess 122 isfurther configured with a wall 126 separated from the surface 92 of thewafer by the space 102D3, the separation being in the axial direction 74(FIG. 2A) to allow region 100 to extend across the lower edge exclusionarea (referred to but not shown as 92EEA). In the desired parallelorientation resulting from the embodiments of the present invention, andwith the lower electrode 54 in the second positional relationship (FIG.2C), the bottom annular recess 122 defines a lower cavity section 128 ofthe chamber cavity 77. The lower cavity section 128 is under the lowersurface 92 of the lower edge environ area 80-C of the wafer 58. Thelower cavity section 128 of the chamber cavity 77 is oriented relativeto the lower edge environ 80-C to define a lower portion of the annularetching region 100 and of the active etching zone 102 to permit etchingof the lower edge environ 80-C. The portion of the lower edge environ80-C that is etched by plasma in the lower cavity section 128corresponds to the bottom wafer surface 92 exposed to the plasma alongthe length L2 shown in FIG. 2C. If there is not to be any etching of thelower surface 92 of the wafer, the value of lower L2 is zero, and thebottom etch defining ring 120 has no lower cavity section 128. In thiscase, the active etch zone 102 would be an exemplary upside-downL-shape. In reverse, if there is not to be any etching of the uppersurface 82 of the wafer, the value of upper L1 is zero, and the top etchdefining ring 110 has no upper cavity section 129. In this case, theactive etch zone 102 would be an exemplary L-shape.

It may be understood that with the use of selected configurations of therings 110 and 120, the base 52 and the upper electrode 53 may beconfigured so that the selected top etch defining ring 110 is mounted onthe upper electrode 53 and the selected bottom ring 120 is mounted onthe lower electrode 54. In the example of the exemplary C-shaped activeetch zone 102, this configuration defines an amount of etching of thetop edge exclusion area 82EEA of the wafer, the amount coinciding withthe length L1 and extending around the axis X. This exemplaryconfiguration also defines an amount of etching of the bottom edgeexclusion area 92EEA of the wafer, the amount coinciding with the lengthL2 and extending around the axis X. This exemplary configuration alsodefines etching of the edge 90 of the exclusion area 82EEA of the wafer,the etching extending around the axis X.

As also described generally above, FIG. 2C shows that by the embodimentsof the present invention, and with the distances 102D1 the same atexemplary distances from the axis X, the distance 102D3 between the wall126 and the lower edge environ 80EEA (e.g., surface 92) is the same whenmeasured at various places around the axis X and within the active etchzone 102. FIG. 2C also shows that with the distances 102D1-102D3 thesame at exemplary distances from the axis X, the distance betweenportion 68X of the configurable ring 110 and surface 126 of theconfigurable ring 120 of the lower electrode 54 is the same whenmeasured at various places around the axis X and within the active etchzone 102. As a result, by the alignment resulting from use of thepresent embodiments, in the active etch zone 102 the action of theplasma on the edge environ 80-C is uniform all around the axis X.

Referring to the drive 62 in more detail, FIG. 2B shows the annularetching region 100 extending in an annular path around the wafer 58. Theetch defining rings 110 and 120 also extend in an annular path aroundthe wafer 58. The inactive etch zone 86 also extends radially across thewafer 58 and axially between the central area 70 and the secondreference surface 60 defined by the center area 68. To assure uniformetching of the edge environ 80 around the axis X, the positionalrelationships between the surfaces 56 and 60 are to be and remainparallel. This means that an established parallelism of the surfaces 56and 60 remains during movement of the upper electrode 53 (via thelinkage 66 and the drive 62) into and in each of the first and secondpositional relationships. Thus, the parallelism remains during themovement between those relationships. This parallelism provides that forthe described uniform removal of the undesired materials 78: (1) theupper surface 82 of the wafer 58 is uniformly in close proximity to thecenter area 68 of the upper electrode 53, and (2) the edge environ 80 iscentered axially in the annular etching region 100 for uniform etchingof the undesired materials 78 to take place.

Before use of the process chamber 50, in conjunction with embodiments ofthe present invention the linkage 66 is adjusted to maintain theestablished parallel and centered positional relationship of thesurfaces 56 and 60, i.e., the established orientation. Referring to theplan view of FIG. 4, the linkage 66 is shown configured in exemplarythree sections 180 spaced around the axis X at exemplary 120 degreeintervals. The following describes one section 180, and is applicable toall of the sections 180. The linkage section 180 cooperates with a firstarm 182 that is secured to the upper electrode 53. The arm 182 is shownin FIGS. 4 & 5A extending horizontally from the upper electrode 53 intothe linkage section 180. With the linkage section 180 loosened asdescribed below, the arm 182 orients the loosened linkage section 180according to how the upper electrode 53 is positioned when the first andsecond reference surfaces 56 and 60 are parallel and centered. Thus,each arm 182 and loosened section 180 may be oriented differently withrespect to the axis X. With this arm and section 180 orientation inmind, reference is made to FIG. 5A that shows a vertical section of atypical linkage section 180 with the oriented arm 182. FIG. 5A shows aloose, or loosened, configuration of the section 180. FIG. 5B shows thesection 180 in a tight, or tightened, configuration.

Still referring to FIG. 5A, the oriented arm 182 is shown extendinghorizontally, and secured to an adjuster block 184. The block 184 isconfigured with a bore 186 to receive an adjuster screw 190 forrotation. Appropriate rotation moves the screw 190 up or down, forexample. The screw 190 is secured to a lock member, or plate, 194.Referring to the loosened configuration of the section 180 shown in FIG.5A, exemplary screw movement up moves the lock member 194 up tocondition the linkage section 180 for orienting of the upper electrode53 relative to the desired existing orientation of the lower electrode54. Before such orienting is performed, the up movement of the lockmember 194 relative to the block 184 provides an alignment space 195Vbetween the drive 62 and the lock member 194. In a general sense, thealignment space 195V allows the upper electrode 53 to assume an alignedparallel relationship with the lower electrode 54, as described below.In detail, the alignment space 195V has an initial value determined byan amount of rotation of the screw 190. The initial value of the space195V is sufficient to allow the upper electrode 53 to assume thataligned parallel relationship with the lower electrode 54 without havingthe lock member 194 touch the drive 62. Thus, the value of the space195V may change from the initial value as the upper electrode 53 isoriented (e.g., vertically) relative to the desired existing orientationof the lower electrode 54. When the orientation is done, each space 195Vof the various sections 180 has some positive value as determined by theoriented upper electrode 53.

Also, the lock member 194 is configured with a slot 195S that defines analignment space 195H between the lock member 194 and a fastener (such asa lock screw 196). The screw 196 is secured in a threaded bore 198 inthe drive 62 at a fixed horizontal location as viewed in FIG. 5A. Theslot 195S is configured so that the alignment space 195H extends aroundthe lock screw 196, separating the lock member 194 from the lock screw196. In general, the slot 195H is configured to define an initial value(FIG. 5A) of the space 195H sufficient to allow the lock member 194 tobe moved by the upper electrode 53 relative to the fastener 196 as theupper electrode 53 assumes the aligned centered relationship withrespect to the lower electrode 54, as described below. For example, suchmovement may be as shown in FIG. 5B (horizontal and to the left),allowing the upper electrode 53 to become aligned and centered withrespect to the axis X on which the lower electrode 54 is centered. Theinitial value of the space 195H is sufficient to allow the upperelectrode 53 to assume that aligned centered relationship with the lowerelectrode 54 without having a wall of the slot 195S touch the screw 196.Thus, the value of the space 195H may change from the initial value asthe upper electrode 53 is oriented (e.g., moved horizontally to theleft) relative to the desired existing orientation of the lowerelectrode 54. When that orientation is done, each space 195H of thevarious sections 180 has some positive value shown in FIG. 5B. Thus, theinitial value of the alignment space 195H may be determined by theamount and direction (left or right) of the anticipated horizontalmovement required to allow the upper electrode 53 to become centeredwith respect to the axis X (and the lower electrode 54) without the slot195S touching the screw 196.

In review, before this orienting, each section 180 is configured withthe alignment spaces 195H and 195V to allow the orienting without havingthe lock member 194 touch the drive 62, and without the wall of the slot195S touching the screw 196. For each section 180, the orienting of theupper electrode 53 relative to the desired existing orientation of thelower electrode 54 may result in the initial values of the alignmentspaces 195V and 195H being changed. FIG. 5B shows that following thatorienting, by rotation of the screw 190 the lock member 194 may be moveddownwardly from the changed up position (as changed by the orienting)until the lock member 194 moves away from the arm 182 and touches thedrive 62. Care is taken to not rotate the screw 190 more than requiredfor the lock member 194 to just touch the drive 62, so that theorientation of the upper electrode 53 is not changed by such lock member194. As the lock member 194 moves to touch the drive 62, the slot 195Sthat defines the alignment space 195H remains spaced from the lock screw196. The lock member 194 is locked to the drive 62 by turning the lockscrew 196 into the threaded bore 198 that extends into the drive 62. Thelock screw 196 extends through the slot 195S and the head of the screw196 presses on the lock member 194 to urge the lock member 194 againstthe drive 62. The lock member 194 held against the drive 62 is held in aposition based on the centered and aligned position (orientation) of theupper electrode 53 with respect to the lower electrode 54. Thus, oncethe lock member 194 is secured to the drive 62, the oriented arm 182does not move relative to the lock member 194 and the upper electrode 53is held by the drive 62 oriented with respect to the lower electrode 54.This locking of the lock member 194 to the drive 62 (with a zero valueof the space 195V, for example, by the lock screw 196 extending throughthe slot 195S and holding the member 194 tight against the drive 62) isreferred to as the tightened (or tight) configuration of the linkagesection 180 of the linkage 66.

As described, each linkage section 180 may be the same. Thus, the samestructure as is described for the one linkage section 180 is providedfor the sections 180 at the other exemplary two spaced locations. Thesame type of rotation of the screw 190, and the same locking of the lockmember 194 to the drive 62, occurs in each section 180. By thecollective action of the various sections 180, the orientation of theupper electrode 53 is not changed by the tightening of the linkagesections 180 into the respective tightened configurations. In thismanner, there is no change in the established parallel and centeredpositional relationship of the surfaces 56 and 60. The many sections 180cooperate to secure the upper electrode 53 to the drive 62 and tomaintain that established parallel and centered positional relationshipof the surfaces 56 and 60.

With the linkage sections 180 secured to the drive 62, the drive 62 maybe operated. One embodiment of the drive 62 may be the wedge assembly64. Referring to FIG. 6, a representative one wedge section 200 of threewedge sections of the wedge assembly 64 is shown. The sections 200 arelocated around the axis X as shown in FIG. 4. Each wedge section 200 maybe the same. Thus, the same structure as is described for the one wedgesection 200 is provided at the other two spaced locations. The oneexemplary section 200 is configured with a first wedge member 202 thatmay be secured by the bolt 196 (FIG. 5B) to the lock member 194. A firstslide 203 holds the wedge member 202 against horizontal movement,permitting the first wedge member 202 to move the lock member 194 up anddown to correspondingly move the arm 182 and the upper electrode 53.This up and down movement is under the action of a second wedge member204 that is connected to a second slide 206 mounted on the base 52. Amotor 208 may be actuated to move the second wedge member 204horizontally on the slide 206 so that a first inclined surface 210 ofthe first wedge member 202 is urged up, for example, by a secondinclined surface 212 of the second wedge member 204. Oppositely, reverseactuation of the motor 208 causes the surface 212 to allow the firstwedge member 202 to move down.

As indicated, the same structure as is described for the wedge sections200 is at each of the three spaced locations. Also, the motor 208 ofeach wedge section 200 may be actuated, for example, by hydraulic fluidfrom a common manifold 214 so that the same fluid pressure is applied toeach motor and the same upward or downward motion is applied at the sametime by each wedge section 200 shown in FIG. 4. In this manner, theupper electrode 53 is moved up and down so that there is no change inthe established parallel and centered positional relationship of thesurfaces 56 and 60, and the upper electrode 53 moves while maintainingthat established parallel and centered positional relationship of thesurfaces 56 and 60.

It may be understood from FIGS. 1 and 6 that by the motor 208 moving thesecond wedge member 204 to the left, the first wedge member 202 is movedup and moves the upper electrode 53 and the second reference surface 60upward away from the first reference surface 56 into the firstpositional relationship (FIG. 2A). Oppositely, by the motor 208 movingthe second wedge member 204 to the right in FIGS. 1 and 6, the firstwedge member 202 is allowed to move down to allow the upper electrodeand the second reference surface 60 to move down toward the firstreference surface 56 into the second positional relationship (FIG. 2C).

In this manner, by the angular shapes of the first wedge member 202 andsecond wedge member 204, the drive 62, via the exemplary wedge assembly64, is configured to apply a driving force through the linkage 66 to theupper electrode 53. This force acts through each linkage section 180equally so that the desired orientation, which is the surfaces 56 and 60parallel and centered (resulting in the upper wafer surface 82 alsoparallel and centered relative to the reference surface 60), ismaintained by the moving first wedge member 202 driving the linkage 66to move the upper electrode 53. In review, one such movement may be theupper electrode 53 moving the second reference surface 60 into thesecond positional relationship (FIG. 2C), wherein the second positionalrelationship is the second reference surface 60 in close proximity withthe first reference surface 56, and thus the upper surface 82 of thewafer 58 also in close proximity to the second reference surface 60, todefine the inactive etch zone 86 in the process chamber 50. Such closeproximity of the second reference surface 60 with the first referencesurface 56 configures the inactive etching zone 86 with the exemplarydimension in the direction of the X axis of about 0.010 inches to about0.020 inches, for example. With the described multiple linkage sections180 and wedge sections 200, such dimension in the direction of movementmay be provided within the dimensional tolerance of about plus or minus0.002 inches. This dimension of the space 84 in the direction ofmovement is repeatable during the relative movement of the upperelectrode 53 and the lower electrode 54, e.g., due to the positionalrelationships between the surfaces 56 and 60 remaining parallel andcentered to assure the uniform etching of the edge environ 80 around theaxis X. In each case of the space 84 and the region 100, there is theabove-described uniformity all around the axis X.

With the above-described structure and operations in mind, the detailsof embodiments of the present invention may readily be understood.Referring first to FIG. 3, the upper electrode 53 is shown with theinsert 69 attached so that the inner reference surface 69I is againstthe third reference surface 61 and the projection 53P is in the recess69R. The ring 110 is shown held on the upper electrode 53 by shoulder132. In this configuration of FIG. 3, the apparatus 100 has been alignedand centered for etching the edge environ 80. Reference to FIG. 7A, incomparison to FIG. 3, shows that some of the structure of FIG. 3 of theapparatus 100 has been removed and is not shown in FIG. 7A. For example,the insert 69 and the ring 110 shown in FIG. 3 have been removed fromthe upper electrode 53. This is done by removing a fastener (not shown)that removably secures the insert 69 to the top electrode 53 with thesurface 69I tight against the surface 61. Such removal of the fastenerreleases the insert 69 so that the shoulder 132 no longer holds the ring110 on the top electrode 53. Also, the wafer 58 shown in FIG. 3 is noton the lower reference surface 56 of the lower electrode 54 and the ring120 has been removed from the lower electrode 54 by lifting the ring 120off the lower electrode 54. Further, as described above, the linkage 66is adjusted into the loose configuration with respect to the upperelectrode 53, i.e., loose, not tightly connected to the base 52 or drive62.

By the absence of the insert 69, the rings 110 and 120, and the wafer58, and with the linkage 66 in the loose configuration, the alignmentspaces 195V and 195H (FIG. 5A) allow the upper electrode 53 to assumethe aligned parallel and centered relationship with respect to the lowerelectrode 54. Thus, the apparatus 100 is in condition to be prepared foran alignment and centering, or orientation, operation according toembodiments of the present invention. In FIG. 7A the upper electrode 53is shown configured with the third reference surface 61 extendingradially away from the axis X. The third reference surface 61 is tobecome aligned with the first reference surface 56 of the lowerelectrode 54. Because the second reference surface 60 and the surface69I of the insert 69 are parallel, upon reassembly of the insert 69 withthe upper electrode 53 to place the surface 69I against the thirdreference surface 61, the second reference surface 60 of the insert 69will also be parallel to the first reference surface 56. Also, if theprojection 53P of the upper electrode 53 is centered with respect to thelower electrode 54, upon reassembly of the insert 69 with the projection53P in the recess 69R, the insert 69 will also be centered with respectto the lower electrode 54.

In FIG. 7A the lower electrode 54 is shown configured with the firstreference surface 56 extending radially to a shoulder 240 havingvertical wall 242. The shoulder 240 may be configured with a circularcross section (in plan view). The upper electrode 53 is shown spacedfrom the lower electrode 54, such that these electrodes may be referredto as spaced electrodes with spaced reference surfaces (i.e. referencesurfaces 56 & 61). A fixture 244 is shown configured with an upperfixture reference surface 246 and a lower fixture reference surface 248parallel to the upper fixture reference surface 246. The lower fixturereference surface 248 is configured to be supported on the first(spaced) reference surface 56 to orient the lower fixture referencesurface 248 and the upper fixture reference surface 246 parallel to thefirst reference surface 56. The upper fixture reference surface 246 isconfigured to support the third (spaced) reference surface 61 to orientthe third spaced reference surface 61 parallel to the upper fixturereference surface 246 and parallel to the first (spaced) referencesurface 56.

FIG. 7A also shows the first (spaced) reference surface 56 configuredwith a periphery 250 spaced from and coaxial with the axis X. Theperiphery 250 may be defined by the vertical wall 242, and in plan viewsimilar to FIG. 2B both are configured with circular cross sections andare concentric with the axis X. The fixture 244 is also shown furtherconfigured with respect to the axis X as follows. The lower fixturereference surface 248 is configured with an annular rim 252 having anannular inner wall 254. The rim 252 & wall 254 extend parallel to thewall 242, overhanging the first reference surface 56. The annular innerwall 254 is configured with respect to the axis X so that with the lowerfixture reference surface 248 supported on the first (spaced) referencesurface 56 the inner wall 254 extends parallel to and coaxial with theaxis X, and surrounds the wall 252 and periphery 250. The inner wall 254is configured spaced from axis X to tightly receive the wall 242 and theperiphery 250 to center the fixture 244 on the first (spaced) referencesurface 56 and relative to the axis X.

With the fixture 244 centered on the first (spaced) reference surface56, and noting that the projection 53P is configured coaxial with anupper electrode axis Y, and with the upper fixture reference surface 246configured with a recess (or opening) 244R extending into the fixture244 coaxially with respect to the axis X, FIG. 7B shows that the fixture244 is configured to center the upper electrode 53 with respect to thelower electrode 54. The recess 244R is configured with a centeringsurface 244C coaxial with the inner wall 254 of the fixture 244.

To mate the upper electrode 53 and the fixture 244 for the alignment andcentering, the upper electrode 53 is moved (e.g., by hand) toward thelower electrode 54 (shown as down in FIG. 7A). The upper electrode 53 isgently placed on the fixture 244 (FIG. 7B). As the upper electrode 53 islowered, the upper electrode 53 is guided side-to-side (perpendicular tothe axis X) to insert the projection 53P into the recess 244R (asallowed by the spaces 195H and 195V. For clarity of illustration, thesurface 244C is shown in FIG. 7B slightly spaced from the wall 53W ofthe projection 53P. The centering surface 244C, and the recess 244R, areconfigured to snugly receive the projection 53P and the wall 53W tocenter the projection 53P with respect to the axis X (i.e., with axis Ycoaxial with axis X). As a result, the projection 53P centers the upperelectrode 53 with respect to the axis X. During this lowering, theinitial values of the alignment spaces 195H and 195V of each section 180(FIGS. 5A & 5B) may be changed as the upper electrode 53 becomesoriented relative to the desired existing orientation of the lowerelectrode 54. To complete the orientation, the upper electrode 53 isfully placed on the fixture 244 so that the third reference surface 61rests on the upper fixture reference surface 246. Upon completion of theorienting of the upper electrode 53 relative to the desired existingorientation of the lower electrode 54, different values of the alignmentspaces 195H and 195V of each section 180 may exist as compared to theinitial values, and these different values result as the third referencesurface 61 becomes parallel to the lower electrode (or first) referencesurface 56, for example, and as the projection 53P becomes centered withrespect to the axis X, all by the action of the fixture 244.

By the use of the insert 69 as described above, it may be understoodthat the wafer process chamber 50 is configured to exclude processing ofthe central area (bracket 70E) of the wafer 58. The central area 70Egenerally has an area corresponding to the area of the upper fixturereference surface 246. Each of the insert 69 and the wafer 58 has athickness in the direction of the axis X. With this in mind, it may beunderstood that the fixture 244 is configured so that the lower fixturereference surface 248 and the upper fixture reference surface 246 arespaced by an alignment distance 270 (FIG. 7A). The alignment distance270 is not shown to scale in FIG. 7A, but is configured having a valueequal to the sum of the thicknesses of the wafer 58 and of the insert 69and of the distance 84 (FIG. 2C) that defines the inactive zone 86 ofthe process chamber 50. Such inactive etch zone 86 excludes theprocessing of the central area 70 of the wafer. Such alignment distance270 is provided so that with the upper electrode 53 resting on fixture244 (as shown in FIG. 7B) during the described alignment and centering,the fixture spaces the third reference surface 61 from the firstreference surface 56 as those two surfaces will be spaced in theoperation of the plasma chamber 50 to etch the edge environ 80 and tonot etch the central area 70 of the wafer 58. Thus, the alignment andcentering occurs with the same spacing of the upper and lower electrodes53 and 54 as is to be used in the processing of the wafer 58. Thisreduces a likelihood of non-uniformity of the spaces 84 & 102D1-D3around the axis X and fosters the desired uniformity described above.For example, the uniform space around the axis X maintains the inactiveetch zone 86 inactive to protect the wafer devices from the plasma.Also, the described centering of the upper electrode 53 with respect tothe lower electrode 54 assures that the radial extent of the annularetching zone 100 will be uniform all of the way around the axis X. Thus,equal etching of the undesired materials 78 will occur on the edgeenviron 80 all around the axis X by the permitted etching operation inthe toroidal etching region 100.

The following operations may be performed to maintain this establishedorientation with the upper reference surface 61 parallel to the lowerelectrode reference surface 56 and the upper electrode 53 centered withrespect to the lower electrode 54 (i.e., aligned and centered withrespect to the axis X). The upper electrode 53 was described above asresting on the fixture 244 (i.e., with the third reference surface 61resting on the upper fixture reference surface 246 and the projection53P snugly received in the recess 244R). Recall that each section 180 ofthe linkage 66 may have been moved during the orientation, and therespective alignment spaces 195H and 195V of each section 180 may havebeen changed as necessary to allow the upper electrode 53 to becomeoriented parallel and centered with respect to the lower electrode 54.With the upper electrode 53 so resting, and with the changed values ofthe spaces 195H and 195V, the linkage 66 is then adjusted as describedabove so that each section 180 becomes configured in the tightenedconfiguration. This tightened configuration secures the upper electrode53 to the drive 62 to maintain the established orientation (the upperreference surface 61 parallel to the lower electrode reference surface56 and the upper electrode 53 centered with respect to the lowerelectrode 54). The drive 62 may then be actuated to lift the upperelectrode 53 off the fixture 244 and back to the position shown in FIG.7A, for example. The fixture 244 may then be removed from the lowerelectrode 54 and the apparatus 100 may then be returned to the exemplaryconfiguration shown in and described above with respect to FIG. 3 oranother configuration shown in the Related Application. As shown in FIG.3, the ring 110 is mounted against and held against the electrode 53.The insert 69 is mounted on and secured to the upper electrode 53centered (by the projection 53P and the recess 69R). The centering iswith respect to the axis X. Upon securing the insert 69 to the upperelectrode 53, the ring 110 is held by the shoulders 132 and 130 on theupper electrode 53. Also, by the now-parallel lower electrode referencesurface 56 and third reference surface 61, the insert surface 69I isparallel to surface 61, resulting in the parallel and centered surfaces56 and 60. The ring 120 and the wafer are placed on the electrode 54,and the aligned and centered apparatus 100 is ready for use to removethe material 78 from the edge environ 80 of the wafer 58.

In review, embodiments of the present invention have been described interms of the apparatus 100 for orienting the upper electrode 53 relativeto a desired existing orientation of the lower electrode 54 in the waferprocess chamber 50. The electrodes 53 and 54 are configured with therespective reference surfaces 56 and 60, and the electrode 53 is alsoconfigured with the third reference surface 61. Referring to FIG. 7A,the fixture 244 may be described as being configured with an upper nest280 and a lower nest 282. The upper nest 280 is configured from theupper fixture reference surface 246 and the centering surface (or upperwall) 244C. The lower nest 282 is configured from the lower fixturereference surface 248 and the inner (or lower) annular wall 254 of theannular rim 252. The lower fixture reference surface 248 is parallel tothe upper fixture reference surface 246. The upper wall 244C is coaxialwith and parallel to the lower wall 254. Each of the upper nest 280 andlower nest 282 is configured to receive at least a portion of therespective upper electrode reference surface 61 and lower electrodereference surface 56. The portion of surface 61 is the projection 53P.The at least a portion of surface 56 is the entire surface 56 betweendiametrically opposed parts of the annular rim 252. The nests 280 and282 orient the upper electrode 53 relative to the desired existingorientation of the lower electrode 54 by aligning the lower fixturereference surface 248 and the upper fixture reference surface 246parallel to the lower electrode reference surface 60 and by centeringthe upper electrode 53 relative to the lower electrode 54.

Embodiments of the present invention may include the apparatus 100configured with the base 52 having a bottom section 290 (FIG. 1) tosupport the lower electrode 54 with the lower electrode referencesurface 56 in the existing orientation as desired for etching the edgeenviron 80. The base 52 is further configured with a frame 292 thatsupports the drive 62. The linkage 66 may be referred to as an adapterin that the linkage 66 is adjustable as described above. Via the linkage66, the adapter is between the frame 292 and the upper electrode 53. Theadapter (linkage 66) is adjustable between the described looseconfiguration and the tight configuration so that in the looseconfiguration the adapter defines the variable alignment spaces 195H and195V between the adapter 66 and the frame 292 (supporting the drive 62).The initial values of the alignment surfaces 195H and 195V may bechanged during the orientation to allow the upper electrode 53 to assumethe aligned parallel and centered relationship with respect to the lowerelectrode 54. As oriented, the alignment spaces 195H and 195V havechanged values as determined by the upper electrode 53 oriented by thenests 280 and 282 relative to the desired existing orientation of thelower electrode 54. The upper fixture reference surface 61 of the upperelectrode 53 is thus in an aligned parallel and centered relationshipwith the lower electrode reference surface 56 so that the insert(second) reference surface 60 is in the same aligned parallel andcentered relationship upon assembly of the insert 69 with the upperelectrode 53.

In further review, in the tight configuration the adapter 66 is securedto the frame 292 (via the drive 62) to eliminate the variable alignmentspaces 195V of each of the sections 180 and to hold each of thealignment spaces 195H tight once the upper electrode 53 is in thecentered orientation, so that the upper electrode 53 is mounted to theframe 292 (via the drive 62) with the upper electrode 53 remaining inthe aligned parallel and centered orientation with respect to thedesired existing orientation of the lower electrode 54 in the waferprocess chamber 50.

It may be understood that the centering of the upper electrode 53relative to the lower electrode 54 is relative to the central axis X ofthe lower electrode 54. The adapter 66 is configured with the pluralityof connectors that are in the form of the sections 180. The sections 180are uniformly spaced around the axis X. Each of the connectors (sections180) is configured to be adjustable between (a) the loose configurationrelative to a portion of the frame 292 (i.e., adjacent to the respectivesection 180) and (b) the tight configuration (shown in FIG. 5B) relativeto the respective portion of the frame 292. In that manner via the tightconfiguration each connector section 180 is secured to the respectiveportion of the frame 292 and the connectors collectively mount the upperelectrode 53 to the frame 292 with the upper electrode 53 remaining inthe aligned parallel and centered orientation with respect to thedesired existing orientation of the lower electrode 54 in the waferprocess chamber 50.

With the uniform spacing of the connectors (sections 180) around theaxis X, the alignment spaces 195H and 195V (e.g., between one of theportions of the frame 292 and one of the respective connectors, orsections, 180) may have values different from the values of thealignment spaces 195H and 195V between another portion of the frame 292and another one of the respective connectors 180. Each of the connectors180 is configured to be adjustable in the direction of the axis X byvarying amounts. In this manner, upon orientation of the upper electrode53, even though the alignment space 195V between one of the portions ofthe frame 292 and the one of the respective connectors 180 has a valuedifferent from the alignment space 195V between another portion of theframe 292 and another one of the respective connectors 180, the upperelectrode 53 may be secured to each portion of the frame 292 thatcorresponds to the respective connector 180. The same applies to thevarious alignment spaces 195H. The securing of the lock members 194 ofthe sections 180 in the tightened configuration mounts the upperelectrode 53 to the portions of the frame 292 with the upper electrode53 remaining in the aligned parallel and centered orientation withrespect to the desired existing orientation of the lower electrode 53 inthe wafer process chamber 50.

As described above, the adapter (section 180) includes the lock member194 configured to be selectably secured by the bolt 196 to (andtouching) the portion of the frame 292, both vertically and horizontallytight. Alternatively, the lock member 194 may be separated by thealignment space 195V from the portion of the frame 292 and may beseparated by the alignment space 195H of the slot 195S from the bolt196. The adapter (linkage 66) includes an adjustment mechanism (e.g., inthe form of the screw 190 mounted on the arm 182 of the upper electrode53 and connected to the plate 194) to define the value (e.g., theinitial value) of the alignment space 195V. The adjustment mechanismalso includes the slot 195S to define the initial value of the alignmentspace 195H. In this manner, during orienting by the nests 280 and 282the upper electrode 53 is enabled to modify the initial values of thealignment spaces 195H and 195V according to the desired existingorientation of the lower electrode 54. The adjustment mechanism(including the screw 190) is further configured to move the spaced lockmember 194 vertically into contact with the portion of the frame 292,and the slot 195S is configured to allow the head of the lock screw 196to urge the lock member 194 against the drive 62 to secure the lockmember 194 to the portion of the frame 292 to hold the upper electrode53 secured to the frame 292 as oriented by the nests 280 and 282.

Embodiments of the present invention may also include the apparatus 100configured with the drive 62 secured to the frame 292 and configured tomove the adapter 66 to move the upper electrode 53 relative to the lowerelectrode 54 as described. For each section 180, the plate 194 isconfigured to be selectably secured by the screw 196 to the respectiveportion of the frame 292 to define the tight configuration or to beseparated by the variable alignment spaces 195H and 195V from therespective portion of the frame 292 to define the loose configuration.These two alignment spaces 195H and 195V of one section 180 may bereferred to as a pair of spaces 195H and 195V. For such pair of spaces,the adjustment mechanism (in the form of the section 180 mounted on theupper electrode 53 and connected to the respective plate 194) definesthe initial values of the variable alignment space 195V, in which aspace 195V is between each of the plates 194 and the portion of theframe 292 in the loose configuration. Such adjustment mechanism furtherin the form of the section 180 mounted on the upper electrode 53 andconnected to the respective plate 194 further defines the initial valueof the variable alignment spaces 195H, in which the space 195H isbetween the slot 195S and the screw 196 is attached to the respectiveportion of the frame 292 in the loose configuration. The initial valuesof the variable alignment spaces 195H and 195V are sufficient to allowthe upper electrode 53 to assume the aligned parallel and centeredrelationship with the lower electrode 54 by varying the initial valuesof the variable alignment spaces 195H and 195V according to (as requiredby) the aligned parallel and centered relationship of the upperelectrode 53 relative to the desired existing orientation of the lowerelectrode 54.

In addition, the apparatus 100 may be described as establishingpositional relationships in the process chamber 50 for protecting theexclusion area within the edge environ 80 of the wafer 58. Embodimentsof the present invention may include the apparatus 100 configured withthe lower electrode 54. The lower electrode 54 may be configured withthe first electrode reference surface 56 to support the wafer 58 to beprocessed on the edge environ 80. The base 52 is configured with theframe 292, the base being configured to mount the lower electrode 54with the first electrode reference surface 56 in a desired orientationfor processing the edge environ 80 and not processing the central area70 of the wafer 58. The process exclusion insert 69 is configured withthe respective parallel first and second insert surfaces 69I and 60 forprotecting the exclusion area (central area 70) from processing. Theupper electrode 53 is configured with the third electrode referencesurface 61 to removably mount the insert 69 with the first insertsurface 69I against the third electrode reference surface 61 and theinsert surface 69I parallel to the electrode reference surface 61. Thealignment fixture 244 is configured for use with the upper electrode 53and lower electrode 54 instead of the insert 69. The fixture 244 isconfigured with the upper fixture reference surface 246 and the lowerfixture reference surface 248 parallel to the upper fixture referencesurface. The fixture 244 is configured so that the lower fixturereference surface 248 mates with the first electrode reference surface56 to support the fixture 244 on the lower electrode 54 with the lowerfixture reference surface 248 and the upper fixture reference surface246 in the desired orientation parallel to the first electrode referencesurface 56. The fixture 244 is configured so that the upper fixturereference surface 246 mates with the third electrode reference surface61 to removably support the upper electrode 53 on the fixture 244 withthe upper (third electrode) reference surface 61 in the desiredorientation parallel to upper fixture reference surface 246.

The adapter in the form of the linkage 66 between the frame 292 and theupper electrode 53 is adjustable between the loose configuration and thetight configuration described above. In the loose configuration theadapter 66 defines the variable alignment spaces 195H and 195V betweenthe adapter 66 and the frame 292. The initial values of the variablealignment spaces 195H and 195V allow the upper electrode 53 supported onthe fixture 244 to be in the desired orientation. In the tightconfiguration the adapter 66 secures the upper electrode 53 fixed to theframe 292 with the upper electrode 53 in the desired orientation topermit removal of the fixture 244 and mounting of the ring 110 andinsert 69 on the upper electrode 53 while the upper electrode remains inthe desired orientation to protect the central area 70 of the wafer 58from processing and to remove the undesired materials 78 from the edgeenviron 80.

The wafer 58 is configured with the wafer thickness as viewed in FIG. 2Cin the direction of the axis X. The insert 69 is also configured with aninsert thickness (i.e., the alignment thickness 270), so that with theupper electrode 53 above the lower electrode 54 in the same verticalposition as the upper electrode 53 was positioned when resting on thefixture 244, the insert 69 defines the inactive process zone 86 betweenthe wafer 58 and the insert 69 (i.e., between the surface 82 and thesurface 60). The inactive process zone 86 has the thickness of the space84. The drive 62 is secured to the frame 292 and is configured to movethe adapter 66 to move the upper electrode 53 relative to the lowerelectrode 54. The fixture 244 is configured so that the lower fixturereference surface 248 and the upper fixture reference surface 246 arespaced by the alignment thickness 270 having a value equal to the sum ofthe wafer thickness and the insert thickness and the thickness of theinactive zone 84 so that the desired orientation of the upper electrode53 is provided with the upper electrode 53 at a first location relativethe lower electrode 54 (i.e., electrode 53 resting on fixture 244). Thefirst location corresponds to the location of the upper electrode 54with the insert 69 mounted to define the inactive process zone 86 havingthe thickness 84 (FIG. 2C).

It may be understood that the lower electrode reference surface 56 isconfigured coaxial with the axis X that may also be referred to as anelectrode axis X. The lower electrode reference surface 56 and thefixture 244 are configured to center the fixture 244 with respect to theaxis X, as described with respect to the wall 254 and the shoulder 240.The fixture 244 and electrode reference surface 61 are configured tocenter the upper electrode 53 with respect to the axis X as describedwith respect to the projection 53P and the centering surface 244C.

It may be understood that embodiments of the present invention mayinclude a method of orienting the upper electrode 53 relative to thelower electrode 54, as defined by a flow chart 300 shown in FIG. 8. Thelower electrode 54 has a desired existing orientation in the processchamber 50, e.g., on the base 52. The orienting is to define the activeprocess (or etching) zone 102 and the inactive process zone 86 in theprocess chamber 50 for processing the wafer 58. The method may move fromstart to an operation 302 of configuring each electrode 53 and 54 with areference surface. A lower electrode reference surface 56 may be in thedesired existing orientation and the upper electrode reference surface61 is to be oriented parallel to the lower electrode reference surface56. The method may move to an operation 304 of temporarily holding theupper electrode reference surface 61 oriented parallel to the lowerelectrode reference surface 56. Such holding may be by the fixture 244as described above. The method may move to an operation 306 of securingthe upper electrode 53 to a drive (e.g., 62) to mount and fix the upperelectrode reference surface 61 parallel to the lower electrode referencesurface 56. Such securing may be by the adapter 66 and the bolts 196 ofthe plates 194, for example, and the method may be done.

Other aspects of the method may include the holding operation 304effective to space the upper electrode reference surface 61 from thelower electrode reference surface 56 by a fixture thickness. The fixturethickness may be equal to the sum of the thickness of the wafer and thethickness 84 of the inactive process zone 86 and a thickness of theprocess exclusion insert 69 secured to the upper electrode referencesurface 61. This holding operation 304 may be understood by reference tothe fixture 244. The fixture is configured so that the lower fixturereference surface 248 and the upper fixture reference surface 246 arespaced by the alignment distance 270 having the value equal to the sumof the thicknesses of the wafer 58 and of the insert 69 and of thedistance 84 (FIG. 2C) that defines the inactive portion of the processchamber 50 (i.e., that defines the inactive etch zone 86) that excludesthe processing of the central area 70 of the wafer. Such alignmentdistance 270 is provided so that when the fixture 244 is resting onsurface 56 as shown in FIG. 7B during the described alignment andcentering, the fixture 244 spaces the third reference surface 61 fromthe first reference surface 56 by an amount that is the same as thosetwo surfaces 56 & 61 will be spaced in the operation of the plasmachamber 50 for the removing of the materials 78 from the edge environ80. The result is that the apparatus of FIG. 2C may uniformly etch theedge environ 80 all around the axis X, and not etch the central area 70of the wafer 58 anywhere around the axis X. Thus, the alignment andcentering by the fixture 244 occurs with the same spacing of the upperand lower electrodes 53 and 54 as is to be used in the processing of thewafer 58, with the benefit described above.

It may be understood that the method may further include operations ofattaching the process exclusion insert 69 to the upper electrode 53after removal of the fixture 244 from the lower electrode 54. Also, anoperation may mount the wafer 58 on the lower electrode referencesurface 56. The drive 62 may be operated to move the upper electrode 53toward the lower electrode 54 to space the process exclusion insert 69(surface 60) from the surface 82 of the wafer 58 by the thickness 84 ofthe inactive process zone 86. As described above, by the use of thefixture 244, the thickness of the inactive process zone 86 may beuniform across the wafer 58 and between the wafer 58 and the processexclusion insert 69, and all around the axis X.

Embodiments of the method may include the holding operation 304including an operation of placing the alignment fixture 244 on the lowerelectrode reference surface 56. The upper electrode 53 may be moved ontothe alignment fixture 244 while allowing the upper electrode 53 tofreely move relative to the drive 62 and the frame 292 (as when thelinkage 66 is in the loose configuration). The various alignment spaces195H and 195V allow such free movement of the upper electrode 53. Theupper electrode 53 may thus become oriented so that the upper electrodereference surface 61 is oriented parallel to the lower electrodereference surface 56 and centered with respect to the axis X, withoutinterference from the drive 62 or the frame.

In view of the above description, apparatus and methods are provided forrapidly orienting the upper electrode 53 with the lower electrode 54that has been placed in a desired orientation. The orienting allowsremoval of the undesired materials uniformly from the edge environ 80 ina manner that removes the undesired materials 78 from only the edgeenviron 80 and does not damage the central area 70. The describedorientation meets the above need to assure that the etching apparatus isaccurately aligned before use, so that in use the apparatus (with therings 110 & 120, for example) results in accurate (e.g., uniform)removal of the undesired materials 78 from the entire edge environ 80,without removing materials from or otherwise damaging the central area68.

The embodiments of the present invention also fill the above-describedneeds by being configured for uniform removal of the undesired materials78 from the entire edge environ 80 (i.e., around the annular edge areaof the upper wafer surface 82 that surrounds the central area 70, andaround the edge 90 of the wafer, and under the edge area along thebottom surface 92 near the edge 90 of the wafer 58). Such uniformremoval is without removing materials from or otherwise damaging thecentral area 70. The operation of the linkage sections 180 so that thereis no change in the established parallel and centered positionalrelationship of the surfaces 56 and 60, and the operation of the manysections 180 that cooperate to secure the top electrode 53 to the base52 while maintaining that established parallel and centered positionalrelationship of the surfaces 56 and 60, contribute to filling theseneeds. For example, this is by establishing and maintaining the closeproximity of the surfaces 56 and 60 uniformly all around the axis X, sothat there is the axially-thin space 84 that defines the chamber cavity77 as being configured with the inactive etching zone 86 uniformlyaround the axis X between the central area 70 of the wafer and thecenter area 68 of the top electrode 53

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

1. Apparatus for orienting an upper electrode relative to a desiredexisting orientation of a lower electrode in a wafer process chamber,each electrode being configured with a reference surface, the apparatuscomprising: a fixture configured with an upper nest and a lower nest,the upper nest being configured with an upper fixture reference surfaceand an upper wall, the lower nest being configured with a lower fixturereference surface and a lower wall, the lower fixture reference surfacebeing parallel to the upper fixture reference surface, the upper wallbeing coaxial with and parallel to the lower wall, each of the uppernest and lower nest being configured to receive at least a portion ofthe respective upper and lower electrode reference surface, the nestsorienting the upper electrode relative to the desired existingorientation of the lower electrode by aligning the lower fixturereference surface and the upper fixture reference surface parallel tothe lower electrode reference surface and by centering the upperelectrode relative to the lower electrode.
 2. Apparatus as recited inclaim 1, further comprising: a base configured with a bottom section tosupport the lower electrode with the lower electrode reference surfacein the existing orientation, the base being further configured with aframe; and an adapter between the frame and the upper electrode, theadapter being adjustable between a loose configuration and a tightconfiguration, in the loose configuration the adapter defining variablealignment spaces between the adapter and the frame to allow the upperelectrode to become oriented in an aligned parallel and centeredrelationship with respect to the lower electrode in the desired existingorientation, the alignment spaces having values determined by the upperelectrode in the oriented relationship.
 3. Apparatus in claim 2, whereinin the tight configuration the adapter is secured to the frame to mountthe upper electrode fixed to the frame with the upper electroderemaining in the oriented relationship.
 4. Apparatus as recited in claim3, wherein the centering of the upper electrode relative to the lowerelectrode is relative to a central axis of the lower electrode, andwherein: the adapter is configured with a plurality of connectors, theconnectors are uniformly spaced around the axis, and each of theconnectors is configured to be adjustable between the looseconfiguration relative to a portion of the frame and the tightconfiguration relative to the respective portion of the frame. 5.Apparatus as recited in claim 4, wherein in the tight configuration eachconnector is secured to the respective portion of the frame and theconnectors collectively mount the upper electrode fixed to the framewith the upper electrode remaining in the oriented relationship withrespect to the desired existing orientation of the lower electrode inthe wafer process chamber.
 6. Apparatus as recited in claim 4, whereinthe uniform spacing of the connectors around the axis allows thealignment space between one of the portions of the frame and one of therespective connectors to have a value different from another alignmentspace between another portion of the frame and another one of therespective connectors.
 7. Apparatus as recited in claim 6, wherein eachof the connectors is configured to be adjustable by varying amounts tomount the upper electrode fixed to the frame even though the alignmentspace between one of the portions of the frame and the one of therespective connectors has a value different from the alignment spacebetween another portion of the frame and another one of the respectiveconnectors, wherein the mounting of the upper electrode fixed to theframe is with the upper electrode remaining in the oriented relationshipwith respect to the desired existing orientation of the lower electrodein the wafer process chamber.
 8. Apparatus as recited in claim 2,wherein: the adapter comprises a plate configured to be selectably fixedto the frame or separated by one of the alignment spaces from the frame;the adapter further comprises an adjustment mechanism mounted on theupper electrode and connected to the plate to move the plate and definean initial value of the one alignment space so that the upper electrodeas oriented by the nests is positioned to modify the initial value ofthe alignment space according to the desired existing orientation of thelower electrode; and the adjustment mechanism is further configured tomove the spaced plate into contact with the frame to enable the plate tobe fixed to the frame to hold the upper electrode as oriented by thenests.
 9. Apparatus as recited in claim 2, wherein: the apparatusfurther comprises a drive secured to the frame and configured to movethe adapter to move the upper electrode relative to the lower electrode;the adapter further comprises a plate configured to be selectablysecured to the drive to define the tight configuration or loosely spacedby a pair of variable alignment spaces with respect to the drive todefine the loose configuration; the adapter further comprises anadjustment mechanism mounted on the upper electrode and connected to theplate to define initial values of the pair of variable alignment spacesin the loose configuration of the adapter; and the adjustment mechanismis configured so that the initial values of the variable alignmentspaces are sufficient to allow the upper electrode to assume the alignedparallel and centered relationship with respect to the lower electrodeby varying the initial values according to the desired existingorientation of the lower electrode.
 10. Apparatus for establishingpositional relationships in a process chamber for protecting anexclusion area within an edge environ of a wafer, the apparatuscomprising: a lower electrode configured with a first electrodereference surface to support a wafer to be processed on the edgeenviron; a base configured with a frame, the base being configured tomount the lower electrode with the first electrode reference surface ina desired orientation for processing the edge environ and not theexclusion area of the wafer; a process exclusion insert configured withparallel first and second insert surfaces for protecting the exclusionarea from processing; an upper electrode configured with a secondelectrode reference surface to removably mount the insert with the firstinsert surface against the second electrode reference surface and thesecond insert surface parallel to the second electrode referencesurface; an alignment fixture configured for use with the upperelectrode and the lower electrode instead of the insert, the fixturebeing configured with an upper fixture reference surface and a lowerfixture reference surface parallel to the upper fixture referencesurface, the fixture being configured so that the lower fixturereference surface mates with the first electrode reference surface tosupport the fixture on the lower electrode with the lower fixturereference surface and the upper fixture reference surface in the desiredorientation, the fixture being configured so that the upper fixturereference surface mates with the second electrode reference surface toremovably support the upper electrode on the fixture with the upperelectrode reference surface in the desired orientation parallel to thefirst electrode reference surface; and an adapter between the frame andthe upper electrode, the adapter being adjustable between a looseconfiguration and a tight configuration, in the loose configuration theadapter defining variable alignment spaces between the adapter and theframe to allow the upper electrode supported on the fixture be in thedesired orientation, in the tight configuration the adapter securing theupper electrode to the frame with the upper electrode in the desiredorientation to permit removal of the fixture and mounting of the inserton the upper electrode while the upper electrode remains in the desiredorientation to protect the exclusion area from processing.
 11. Apparatusas recited in claim 10, wherein the wafer is configured with a waferthickness, and wherein: the insert is configured with an insertthickness for defining an inactive process zone between the wafer andthe insert, the inactive process zone having an inactive zone thickness;the apparatus further comprises a drive secured to the frame andconfigured to move the adapter to move the upper electrode relative tothe lower electrode; and the fixture is configured so that the lowerfixture reference surface and the upper fixture reference surface arespaced by an alignment distance having a value equal to the sum of thewafer thickness and the insert thickness and the thickness of theinactive zone so that the desired orientation of the upper electrode isprovided with the upper electrode at a first location relative the lowerelectrode, the first location corresponding to the location of the upperelectrode with the insert mounted for defining the inactive process zonehaving the inactive zone thickness.
 12. Apparatus as recited in claim10, wherein: the first electrode reference surface is configured coaxialwith an electrode axis; the first electrode reference surface and thefixture are configured to center the fixture with respect to the axis;and the fixture and the second electrode reference surface areconfigured to center the upper electrode with respect to the axis.